The invention relates to a pressure welding apparatus and pressure welding method for pressure-welding electric wires to the pressure-welding parts of pressure-welding contacts.
Soldering, press-bonding and pressure welding, etc., have been used in the past as methods for connecting electric wires to contacts. Among these methods, pressure welding is advantageous from the standpoint of the productivity of the connecting work. Pressure welding is spreading even in the Japanese automobile industry, in which pressure welding has not been very widely used in the past. The examples shown in FIGS. 8 through 11 are universally known as examples of a pressure-welding connector for use in automobiles and a pressure welding apparatus for use with this connector (Japanese Patent Application Kokai No. 10-326633).
In FIG. 8, the pressure-welding connector 100 comprises a plurality of contacts 120, each of which has a contact part (not shown in the figures) and a pressure-welding part 122, and an insulating housing 110 which has a plurality of cavities 112 that accommodate the contacts 120. The housing 110 covers the contact parts of the contacts 120 in the front engaging part 114, but opens at the top in the rear so that the pressure-welding parts 122 of the contacts 120 are exposed. Cutouts 118 are formed in housing partition walls 116 on both sides of the cavities 112 in positions adjacent to the pressure-welding parts 122. These cutouts 118 are used to accommodate side-surface retaining parts 132 which are installed inside the pressure-welding pressing die 130 shown in FIG. 9 so that these side-surface retaining parts 132 are driven downward by springs 134. In order to connect the electric wires 140 and respective contacts 120, the electric wires 140 are first positioned on the pressure-welding parts 122 as shown in FIG. 10. Next, when the pressure-welding pressing die 130 is lowered, the side-surface retaining parts 132 advance into the cutouts 118, and the stuffers 136 of the pressure-welding pressing die 130 contacts the electric wires 140. Then, when the pressure-welding pressing die 130 is further lowered, the stuffers 136 press-fit (pressure-weld) the electric wires 140 inside the pressure-welding parts 122 as shown in FIG. 11. In this pressure-welding process, the side-surface retaining parts 132 that have advanced into the cutouts 118 support the side walls 124 of the pressure-welding parts 122 from the sides. Accordingly, the pressure-welding parts 122 can be prevented from opening even in cases where no contacts 120 are accommodated in the cavities 112 adjacent to the cavities 112 in which the pressure-welded contacts 120 are accommodated.
However, as the installation pitch of contacts 120 has become smaller (e.g., a pitch of 2.2 mm) with the increase in density seen in connectors in recent years, it has become unavoidably necessary to reduce the thickness of the partition walls 116 between the cavities 112. Since cutouts 118 which allow the entry of the side-surface retaining parts 132 are formed in the partition walls 116, the spatial distance between adjacent contacts 120 at the positions of the cutouts 118 is extremely small. As a result, there is a danger that electrical current flowing through the contacts 120 will leak via the cutouts 118.
Accordingly, it is an object of the invention to provide a pressure welding apparatus and pressure welding method which prevents the pressure-welding parts of the contacts from opening, without forming cutouts in the partition walls between the cavities of the connector housing.
The invention is a pressure welding apparatus for pressure welding a wire to a contact that is disposed in one cavity of a housing having a plurality of side-by-side cavities that are separated by partition walls. The pressure welding apparatus comprises a pressing die assembly having a stuffer that is associated with the one cavity, and a pair of pins disposed on respective opposite sides of the stuffer. The pins are resiliently biased to protrude beyond an end of the stuffer. The pins are arranged to enter respective cavities that are adjacent to said one cavity and to support the partition walls that are between said one cavity and said adjacent cavities.
According to one aspect, each of the pins has a width that is substantially equal to a width of its corresponding said adjacent cavity.
According to another aspect, each of the adjacent cavities holds a contact having opposite side walls, and each of the pins has a width that is substantially equal to a width between the opposite side walls.
According to a further aspect, each of the pins has a cross-sectional shape that is circular.